> The maturation of the reproductive organs appears to be driven by secretions from the optic gland. These same secretions, it seems, inactivate the digestive and salivary glands, which leads to the octopus starving to death.
> In 1977, researchers removed this gland and found that the octopus' mothering instincts disappeared. She abandoned her eggs, started feeding again, and went on to live a much longer life.
As a reproductive strategy for an (arguably) intelligent animal ... this makes me feel sad. However there's plenty of octopuses around so in evolutionary terms it's a strategy that works.
As for the males - and this is the point at which my anthropomorphic 'yuk' reflex goes into overdrive - they die soon after their first successful sexual encounter. Males store sperm in one of their arms. For some species, 'sex' involves detaching that arm and giving it to the female to keep for later use. Then they wander off and die. Possibly from disappointment.
I think octopuses are a good counter-example to the concept of Intelligent design.
edit: to clarify, they're MAGNIFICENT creatures, and are a testament to the unfeeling unemotional beauty of actual Evolution - it has no plan. It is random. It only works because of odds. That some traits get selected for more frequently ON AVERAGE.
Sometimes that can lead to some interesting places...octopus, platypus, narwals. Hell, most animals are RIDICULOUS when you get down close.
But this curse of the octopus's intelligence being severely artificially limited so they can't progress and evolve.
Maybe the meaning of life is for us to use our technology and medicine to help the Octopuses live long and fulfilling lives and put them on a path to continuing evolution and together the human and octopuses species are meant to conquer the galaxy.
Alas, in this dimension, we fucked up and destroyed their habitat instead.
There's a Radiolab episode about this. An Octopus mother brooding her eggs for month on end and then dying just when the eggs hatched. Episode title is Octomom.
I suppose it's true that spaying and neutering is technically disabling an animal. I guess not having pets would be the best solution for people who consider spay/neuter harmful. But for people who are okay with the idea of pets, and who do not wish to breed their pets, many find the control of breeding instincts and behavior helpful, not to mention the long term health benefits for the pets.
>> whats the evolutionary reason for something like that?!
You can never really know the reason with evolution because every plausible effect is in play and part of the optimization process. Having said that, one reason for adults to die may be to conserve resources (food) for the young in times/areas of scarcity. Another may be to prevent excess breeding by an individual, which may reduce genetic diversity. There are probably other viable reasons as well.
Lesser genetic diversity is always bad for survival: with clonal species like the bananas we cultivate, for instance, a single pathogen can endanger the whole population.
The less diverse the population, the less likely timely mutations will help protect it. Incidentally, our modern society is pretty diverse, especially as we protect those who couldn't otherwise survive without modern medicine.
Ah, I better see your point. Well, that adaptation has to be selected for at some point of course.
Among a single species, with a 50/50 split of a genetically diverse and homogeneous population, if you eliminate 10% of the former and 75% of the latter, the split becomes 80/20. If that distinction stemmed from genetic factors, you have selected for diversity.
Genetic diversity isn't only advantageous to the population. It's advantageous for the individuals that carry it, depending on the circumstances. Therefore it can easily be selected for.
Surely if genetic variation is introduced primarily by the breeding process, any factors which have a effect against like (competing for food, less genetic variation), etc, are going to get selected against? I have always thought this was the reason behind human lifespans - in neolithic times, up to 33 years. Just enough time to mate and raise another individual to maturity.
There doesn't have to be a use for an evolutionary trait. It can be an utterly useless feature. The fact that it persists in this fleeting moment we co-exist with it in this particular million years, only shows that a feature hasn't been rendered extinct. Yet.
But of course, I believe that biologists can construct a cladistic tree that can calibrate how long a particular trait might have been around.
I read an entire book on this! It’s because their expected time-to-predation is very short. Genes that are deleterious to long life-span aren’t selected against and, thus, accumulate. (“Other Minds” by Peter Smith.)
I know sharks are a significant predator where I live and in places I’ve seen in documentaries. I’d assume that’s the case around all of the oceans since sharks and octopuses occur together everywhere. I’m not sure if that’s the case in the deep sea, though.
One other evolutionary reason is that octopuses lay 20-100 thousand eggs that one time. They really don't need to carry on and produce another batch. Of course, most of those larva are eaten before they make it to maturity, just like many other sea creatures..
